Forward isolation in radio-frequency switches using internal regulator

ABSTRACT

A radio-frequency switch includes a series field-effect transistor, a shunt field-effect transistor having a gate node, and shunt arm control circuitry configured to receive an internal regulator voltage and provide the internal regulator voltage to the gate node of the shunt field-effect transistor when the radio-frequency switch is in a stand-by mode of operation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/839,774, filed Aug. 28, 2015, entitled SWITCH STAND-BY MODE ISOLATIONIMPROVEMENT, which claims priority to U.S. Provisional Application No.62/043,833, filed on Aug. 29, 2014, entitled SWITCH STAND-BY MODEISOLATION IMPROVEMENT, the disclosures of which are hereby incorporatedby reference in their entirety.

BACKGROUND Field

The present disclosure generally relates to the field of electronics,and more particularly, to radio-frequency (RF) devices.

Description of Related Art

In RF devices, RF switching devices can be used to route electricalsignals. RF isolation between can be an important parameter in certainRF devices.

SUMMARY

In some implementations, the present disclosure relates to asemiconductor die including a semiconductor substrate and aradio-frequency (RF) switch including one or more series field-effecttransistors (FETs) and one or more shunt FETs, each of the one or moreseries FETs and one or more shunt FETs having a respective gate node,the RF switch being configured to receive an RF signal from a poweramplifier module and provide the RF signal to an antenna. Thesemiconductor die may further include an internal regulator voltagesource configured to provide an internal regulator voltage when the RFswitch is in a stand-by mode and shunt arm control circuitry configuredto provide the internal regulator voltage to the gate nodes of the oneor more shunt FETs when the RF switch is in the stand-by mode.

In certain embodiments, the RF switch is in a stand-by mode when thepower amplifier module is powered-down. The internal regulator voltagemay be between 1.0 and 1.5 V.

The shunt arm control circuitry may be further configured to provide avoltage regulator voltage to the gate nodes of the one or more shuntFETs when the RF switch is in an active ON mode. Om certain embodiments,the shunt arm control circuitry is further configured to provide thevoltage regulator voltage to the gate nodes of the one or more shuntFETs when the voltage regulator voltage is greater than the internalregulator voltage and to provide the internal regulator voltage to thegate nodes of the one or more shunt FETs when the voltage regulatorvoltage is less than the internal regulator voltage. The shunt armcontrol circuitry may be further configured to provide a negativevoltage to the gate nodes of the one or more shunt FETs when the RFswitch is in an active OFF mode.

In certain embodiments, the shunt arm control circuitry includes aplurality of pFETs connected in series. A drain or source of one of theplurality of pFETs may be connected to at least one of the gate nodes ofthe one or more shunt FETs. Furthermore, a gate of one of the pluralityof pFETs is connected to a voltage regulator voltage that is greaterthan approximately 2.0 V when the power amplifier module is fullypowered.

Certain embodiments disclosed herein provide a shunt arm control circuitfor a switching device including a first input node connected to avoltage regulator voltage, a second input node connected to an internalregulator voltage, a third input node connected to a charge pumpvoltage, and connection circuitry configured to connect the first inputnode to gates one or more shunt FETs of a switching device when theswitching device is in an active ON mode, to connect the second inputnode to the gates of the one or more shunt FETs when the switchingdevice is in a stand-by mode, and to connect the third input node to thegates of the one or more shunt FETs when the switching device is in anactive OFF mode.

In certain embodiments, the switching device is in the stand-by mode,the switching device is not fully powered. When the switching device isin the stand-by mode, the internal regulator voltage may be greater thanthe voltage regulator voltage. When the switching device is in theactive ON mode or the active OFF mode, the switching device may besubstantially powered-up. In certain embodiments, when the switchingdevice is in the active ON mode or the active OFF mode, the voltageregulator voltage is greater than the internal regulator voltage.

The internal regulator voltage may be generated from a bandgapreference. In certain embodiments, the internal regulator voltage isbetween 1.0 and 1.5 V.

The shunt arm control circuit may further include a plurality of pFETsconnected in series. In certain embodiments, a drain or source of one ofthe plurality of pFETs is connected to at least one of the gates of theone or more shunt FETs. A gate of another of the plurality of pFETs maybe connected to the first node and a drain or source of the other of theplurality of pFETs may be connected to the second node.

In some implementations, the present disclosure relates to aradio-frequency (RF) device including a transceiver configured togenerate an RF signal, a power amplifier (PA) in communication with thetransceiver, the PA configured to amplify the RF signal, and an RFswitch including one or more series field-effect transistors (FETs) andone or more shunt FETs, each of the one or more series FETs and one ormore shunt FETs having a respective gate node, the RF switch beingconfigured to receive the amplified RF signal and provide the amplifiedRF signal via the one or more series FETs. The RF device may furtherinclude an internal regulator voltage source configured to provide aninternal regulator voltage when the RF switch is in a stand-by mode,shunt arm control circuitry configured to provide the internal regulatorvoltage to the gate nodes of the one or more shunt FETs when the RFswitch is in the stand-by mode, and an antenna configured to receive theamplified RF signal and facilitate transmission of the amplified RFsignal. In certain embodiments, the RF device includes a wirelessdevice. The wireless device may be, for example, a cellular phone.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are depicted in the accompanying drawings forillustrative purposes, and should in no way be interpreted as limitingthe scope of the inventions. In addition, various features of differentdisclosed embodiments can be combined to form additional embodiments,which are part of this disclosure. Throughout the drawings, referencenumbers may be reused to indicate correspondence between referenceelements.

FIG. 1 is a diagram of a radio-frequency (RF) switch according to one ormore embodiments.

FIG. 2 is a diagram of a RF switch according to one or more embodiments.

FIG. 3 is a diagram of an RF core of an RF switch according to one ormore embodiments.

FIG. 4 is a diagram of an RF core of an RF switch according to one ormore embodiments.

FIG. 5A is a diagram of an example switching device in a stand-by modeof operation according to certain embodiments of the present disclosure.

FIG. 5B is a diagram of an example switching device in an ON mode ofoperation according to certain embodiments of the present disclosure.

FIG. 5C is a diagram of an example switching device in an OFF mode ofoperation according to certain embodiments of the present disclosure.

FIG. 6 is a diagram of a shunt arm control circuit in accordance withone or more embodiments.

FIG. 7 is a graph illustrating potential performance values for stand-bymode isolation for a system incorporating stand-by mode isolation usingan internal voltage regulator according to one or more embodiments.

FIG. 8 is a graph showing possible improvement in performance for afront-end module implementing stand-by mode isolation according to oneor more embodiments.

FIGS. 9A and 9B illustrate a plan view and side view, respectively, ofan RF module according to one or more embodiments.

FIG. 10 schematically depicts an example wireless communication devicehaving one or more advantageous features described herein according toan embodiment.

DETAILED DESCRIPTION

While certain embodiments are described, these embodiments are presentedby way of example only, and are not intended to limit the scope ofprotection. Indeed, the novel methods and systems described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the methods and systemsdescribed herein may be made without departing from the scope ofprotection.

FIG. 1 schematically shows a radio-frequency (RF) switch 100 configuredto switch one or more signals between one or more poles 102 and one ormore throws 104. In some embodiments, such a switch can be based on oneor more field-effect transistors (FETs) such as silicon-on-insulator(SOI) FETs. When a particular pole is connected to a particular throw,such a path is commonly referred to as being closed or in an ON state.When a given path between a pole and a throw is not connected, such apath is commonly referred to as being open or in an OFF state.

FIG. 2 shows that in some implementations, the RF switch 100 of FIG. 1can include an RF core 110 and an energy management (EM) core 112. TheRF core 110 can be configured to route RF signals between the first andsecond ports. In the example single-pole-double-throw (SPDT)configuration shown in FIG. 2, such first and second ports can include apole 102 a and a first throw 104 a, or the pole 102 a and a second throw104 b.

In some embodiments, the EM core 112 can be configured to supply, forexample, voltage control signals to the RF core 110. The EM core 112 canbe further configured to provide the RF switch 100 with logic decodingand/or power supply conditioning capabilities.

In some embodiments, the RF core 110 can include one or more poles andone or more throws to enable passage of RF signals between one or moreinputs and one or more outputs of the switch 100. For example, the RFcore 110 can include a single-pole double-throw (SPDT or SP2T)configuration, as shown in FIG. 2.

In the example SPDT context, FIG. 3 shows a more detailed exampleconfiguration of an RF core 110. The RF core 110 is shown to include asingle pole 102 a coupled to first and second throw nodes 104 a, 104 bvia first and second transistors (e.g., FETs) 120 a, 120 b. The firstthrow node 104 a is shown to be coupled to an RF ground via a FET 122 ato provide shunting capability for the node 104 a. Similarly, the secondthrow node 104 b is shown to be coupled to the RF ground via a FET 122 bto provide shunting capability for the node 104 b.

In an example operation, when the RF core 110 is in a state where an RFsignal is being passed between the pole 102 a and the first throw 104 a,the FET 120 a between the pole 102 a and the first throw node 104 a canbe in an ON state, and the FET 120 b between the pole 102 a and thesecond throw node 104 b can be in an OFF state. For the shunt FETs 122a, 122 b, the shunt FET 122 a can be in an OFF state so that the RFsignal is not shunted to ground as it travels from the pole 102 a to thefirst throw node 104 a. The shunt FET 122 b associated with the secondthrow node 104 b can be in an ON state so that any RF signals or noisearriving at the RF core 110 through the second throw node 104 b isshunted to the ground so as to reduce undesirable interference effectsto the pole-to-first-throw operation.

Although the foregoing example is described in the context of asingle-pole-double-throw configuration, it will be understood that theRF core can be configured with other numbers of poles and throws. Forexample, there may be more than one pole, and the number of throws canbe less than or greater than the example number of two.

In the example of FIG. 3, the transistors between the pole 102 a and thetwo throw nodes 104 a, 104 b are depicted as single transistors. In someimplementations, such switching functionalities between the pole(s) andthe throw(s) can be provided by switch arm segments, where each switcharm segment includes a plurality of transistors such as FETs.

An example RF core configuration 130 of an RF core having switch armsegments is shown in FIG. 4. In the example, the pole 102 a and thefirst throw node 104 a are shown to be coupled via a first switch armsegment 140 a. Similarly, the pole 102 a and the second throw node 104 bare shown to be coupled via a second switch arm segment 140 b. The firstthrow node 104 a is shown to be capable of being shunted to an RF groundvia a first shunt arm segment 142 a. Similarly, the second throw node104 b is shown to be capable of being shunted to the RF ground via asecond shunt arm segment 142 b.

In an example operation, when the RF core 130 is in a state where an RFsignal is being passed between the pole 102 a and the first throw node104 a, all of the FETs in the first switch arm segment 140 a can be inan ON state, and all of the FETs in the second switch arm segment 104 bcan be in an OFF state. The first shunt arm 142 a for the first thrownode 104 a can have all of its FETs in an OFF state so that the RFsignal is not shunted to ground as it travels from the pole 102 a to thefirst throw node 104 a. All of the FETs in the second shunt arm 142 bassociated with the second throw node 104 b can be in an ON state sothat any RF signals or noise arriving at the RF core 130 through thesecond throw node 104 b is shunted to the ground so as to reduceundesirable interference effects to the pole-to-first-throw operation.

Again, although described in the context of an SP2T configuration, itwill be understood that RF cores having other numbers of poles andthrows can also be implemented.

In some implementations, a switch arm segment (e.g., 140 a, 140 b, 142a, 142 b) can include one or more semiconductor transistors such asFETs. In some embodiments, an FET may be capable of being in a firststate or a second state and can include a gate, a drain, a source, and abody (sometimes also referred to as a substrate. In some embodiments, anFET can include a metal-oxide-semiconductor field effect transistor(MOSFET). In some embodiments, one or more FETs can be connected inseries forming a first end and a second end such that an RF signal canbe routed between the first end and the second end when the FETs are ina first state (e.g., ON state).

Examples of FET Structures and Fabrication Process Technologies

A switching device can be implemented on-die, off-die, or somecombination thereof. A switching device can also be fabricated usingvarious technologies. In some embodiments, RF switching devices can befabricated with silicon or silicon-on-insulator (SOI) technology.

As described herein, an RF switching device can be implemented usingsilicon-on-insulator (SOI) technology. In some embodiments, SOItechnology can include a semiconductor substrate having an embeddedlayer of electrically insulating material, such as a buried oxide layerbeneath a silicon device layer. For example, an SOI substrate caninclude an oxide layer embedded below a silicon layer. Other insulatingmaterials known in the art can also be used.

Implementation of RF applications, such as an RF switching device, usingSOI technology can improve switching device performance. In someembodiments, SOI technology can enable reduced power consumption.Reduced power consumption can be desirable in RF applications, includingthose associated with wireless communication devices. SOI technology canenable reduced power consumption of device circuitry due to decreasedparasitic capacitance of transistors and interconnect metallization to asilicon substrate. Presence of a buried oxide layer can also reducejunction capacitance or use of high resistivity substrate, enablingreduced substrate-related RF losses. Electrically isolated SOItransistors can facilitate stacking, contributing to decreased chipsize.

In some SOI FET configurations, each transistor can be configured as afinger-based device where the source and drain are rectangular shaped(in a plan view) and a gate structure extends between the source anddrain like a rectangular shaped finger. FET devices described herein caninclude a p-type FET or an n-type FET. Thus, although some FET devicesare described herein as p-type devices, it will be understood thatvarious concepts associated with such p-type devices can also apply ton-type devices, and vice versa.

A pMOSFET can include an insulator layer formed on a semiconductorsubstrate. The insulator layer can be formed from materials such assilicon dioxide or sapphire. An n-well may be formed in the insulatorsuch that the exposed surface generally defines a rectangular region.Source (S) and drain (D) may be p-doped regions whose exposed surfacesgenerally define rectangles. S/D regions can be configured so thatsource and drain functionalities are reversed. In certain embodiments, agate (G) can be formed on the n-well so as to be positioned between thesource and the drain.

In certain embodiments, a drain of one FET acts as a source of itsneighboring FET. Thus, a multiple-finger FET device as a whole canprovide a voltage-dividing functionality. For example, an RF signal canbe provided at one of the outermost p-doped regions; and as the signalpasses through the series of FETs, the signal's voltage can be dividedamong the FETs.

In some implementations, a plurality of multi-finger FET devices can beconnected in series as a switch to, for example, further facilitate thevoltage-dividing functionality. A number of such multi-finger FETdevices can be selected based on, for example, power handlingrequirement of the switch.

Stand-by Mode Isolation

In certain switching devices and modules, OFF-state isolation is aperformance parameter that can provide a measure of the RF isolationbetween an input port and an output port of an RF switch. In someembodiments, OFF-state isolation can be a measure of the RF isolation ofa switching device while the switching device is in a state where aninput port and an output port are electrically isolated, for examplewhile the switching device is in an OFF state. Increased switchingdevice isolation can improve RF signal integrity. In certainembodiments, an increase in isolation can improve wireless communicationdevice performance.

Isolation can be negatively affected by parasitic capacitances intransistor devices. For example, when a transistor 122 a or 122 b ofFIG. 3 is in an OFF state, wherein drain-to-source current in thetransistor is substantially inhibited, parasitic capacitances may existbetween one or more terminals of the transistor, which can negativelyimpact performance of the RF core 110. Various parasitic capacitances ofthe transistors 120 a, 120 b may be created at least in part by thedepletion regions between source/drain and bulk substrate of thetransistors.

Certain embodiments of RF communications systems/modules include aswitching device, as described above, configured to receive an RF inputsignal corresponding to an output signal of a power amplifier module,such as a GSM power amplifier module, for example. An examplecommunication device including one or more power amplifier modulesconnected to one or more switching modules is described in furtherdetail below with respect to FIG. 11. The output power from the poweramplifier module(s) may be controlled at least in part by a Vramp signalthat also controls the associated power-versus-time (PVT) mask.

At the beginning of a power-up sequences, the power amplifier module maydesirably be configured to deliver no more than, for example, −55 dBmoutput power to an associated antenna port while the input power is, forexample, 6 dBm. Such configurations and/or requirements may necessitatethe utilization of relatively high-isolation switch(es). For example,certain switching devices as described herein may be configured toprovide approximately 61 dB or more isolation.

High forward isolation performance in switching devices forpower-up/stand-by mode isolation may be achieved in various ways. As oneexample, switching devices may be designed using HBT die having goodisolation. However, such designs may be associated with certainsimulation difficulties. Another example method may involve increasingisolation in the laminate. However, such designs may introduceundesirable size penalties and/or necessitate architecturalmodifications. In certain embodiments, switching between transmit (Tx)and receive (Rx) modes before the power amplifier module is powered onmay improve stand-by mode isolation. However, such a configuration mayrequire undesirable modifications in control logic.

Certain embodiments disclosed herein provide switch isolationimprovement without requiring high-isolation HBT dies and/or laminates,through the implementation of stand-by (STB) mode isolation improvementin shunt arm gate voltage control circuitry. FIG. 5A is a diagram of anexample switching device 500 including an RF core 710 having series andshunt switch arm segments. Although each of the series arm and the shuntarm of the RF core 710 shows only a single switch, such switch maycomprise a plurality transistors, each having a respective gate. At agiven time, the circuit 500 may be in an active or inactive state. In anactive state, the circuit 500 is configured to receive a voltageregulation signal and/or a charge pump voltage signal, wherein thevoltage regulation signal provides a gate voltage for turning one of theseries and shunt arms ON, whereas the charge pump voltage signal mayprovide a gate voltage for turning the other of the series and shuntarms OFF. That is, the active state may comprise two states with respectto the RF core 710, an ON state, in which the series arm is ON and theshunt arm is OFF, and an OFF state, in which the shunt arm is ON and theseries arm is OFF. Such OFF and On states are illustrated in FIGS. 5Band 5C. One or more of the transistors in the circuit 500 may befloating body transistors, which may allow for relatively quickswitching performance. The charge pump voltage (Vcp) may be provided bya charge pump comprising a DC-to-DC converter configured to utilize oneor more capacitors as energy storage elements for creating a low-voltagepower source from the power supply rail.

The gates of the respective series and shunt arm transistors arecontrolled by a series arm control circuit 718 and a shunt arm controlcircuit 717, respectively. In particular, the series arm control circuit718 may be configured to selectively connect the gate of one or moretransistors of the series arm of the RF core 710 to a voltage regulatorsignal (Vreg) or a charge pump voltage (Vcp). In certain embodiments,the series arm control circuit 718 may be further configured toselectively connect the series gate(s) to ground. Vreg may be anydesirable value designed to cause the series and/or gate transistor(s)to operate in a substantially ON state, wherein an electrical currentcan flow between drain and source nodes of the transistor(s). Forexample, during active operation, Vreg may have a value of approximately2.3 V, 2.5 V, or some other value. The value of Vcp, on the other hand,may advantageously be less than or equal to 0 V. For example, Vcp mayhave a value of approximately −2.1 V in certain embodiments, or someother value.

In a stand-by state of operation, there may be substantially no voltagesupplied at the Vreg and/or Vcp nodes. For example, the stand-by statemay correspond to a state in which the switch device and/or anassociated power amplifier module are substantially powered-down, or ina state of powering-up. As described above, it may be desirable incertain embodiments to activate the shunt arm of the RF core 710 duringstand-by mode in order to improve stand-by isolation. However, without asubstantial positive voltage available at the Vreg node, it may not bepossible to sufficiently switch on the shunt arm transistor(s) usingVreg.

In certain embodiments, the circuit 500 may be configured to receivepower for activating the shunt arm transistor(s) from a separate sourceother than Vreg in order to improve stand-by isolation. For example,certain embodiments disclosed herein provide utilization of an internalbandgap voltage regulator for activating shunt arm transistor(s) toimprove stand-by isolation.

The internal regulator voltage may be derived from a bandgap voltagereference, which may provide a temperature-independent,substantially-fixed voltage. The internal regulator voltage may besubstantially independent of power supply variations, temperaturechanges and/or device loading. The bandgap reference may provide anoutput voltage around 1.25 V, and may be derived from the voltagedifference between semiconductor p-n junctions, which may be used togenerate a proportional to absolute temperature (PTAT) current in afirst resistor. This current may be used to generate a voltage in asecond resistor. This voltage may in turn be added to the voltage of ajunction. The ratio between the first and second resistors may beselected such that the first order effects of the temperature dependencyof the junction and the PTAT current substantially cancel out. Theresulting voltage may be approximately 1.2-1.3 V, depending on theparticular technology and/or circuit design. In certain embodiments, thereference voltage is used to generate an internal regulator voltage ofapproximately 1.21 V. The internal regulator voltage may be availableeven when the voltage regulator Vreg is powered down.

FIG. 5A shows the stand-by mode operation according to certainembodiments of the present disclosure. As shown, in stand-by mode, theseries arm transistor(s) of the RF core 710 may be OFF. Therefore, theseries arm control circuit 718 may be tied to ground or otherwise beconnected to a voltage signal at or near 0 V, which may produce asubstantially open series arm circuit.

The shunt arm control circuit 717 may be configured to provide aninternal regulator voltage (Vir) to the gate(s) of the shunt armtransistor(s) when the circuit 500 is in stand-by mode. The shunt armcontrol circuit 500 may be provided in parallel with an existingcircuit, which provides a high voltage (Vreg) to control the shunt armwhen the circuit 500 is in an OFF mode and a low voltage (Vcp) tocontrol the shunt arm when the circuit 500 is in an ON state. In certainembodiments, the circuit 500 is configured to disconnect from theexisting shunt arm control circuit during stand-by mode.

FIG. 5B illustrates the circuit 500 in an active ON mode of operation.In ON mode, the circuit 500 receives a high voltage (e.g., 2.5 V) at theVreg node and such voltage is provided to the series arm transistorgate(s) of the RF core by the series arm control circuit 718 in order toturn on the series arm. Furthermore, the shunt arm control circuit 717provides a low voltage (Vcp) to the shunt arm transistor gate(s) inorder to turn off the shunt arm.

FIG. 5C illustrates the circuit 500 in an active OFF mode of operation.In OFF mode, the circuit 500 receives a high voltage (e.g., 2.5 V) atthe Vreg node and such voltage is provided to the shunt arm transistorgate(s) of the RF core by the shunt arm control circuit 717 in order toturn on the shunt arm. Furthermore, the series arm control circuit 718provides a low voltage (Vcp) to the series arm transistor gate(s) inorder to turn off the series arm.

FIG. 6 is a diagram of a shunt arm control circuit 617 in accordancewith an embodiment. The circuit 617 may be used for floating-bodyswitching to turn on the shunt arm 624 during stand-by mode, asdescribed herein. In certain embodiments, the circuit 617 is configuredin parallel with an existing shunt arm control circuit.

The circuit may include a first node configured to receive a voltageregulator signal Vreg. The circuit 617 further includes a second nodeconfigured to receive an internal regulator voltage. The circuit 617 mayfurther include one or more nodes connected to one or more shunt armtransistor gates to provide a control signal thereto. The circuit 617may be configured to provide the internal regulator voltage (e.g., 1.2V) to the shunt arm when the voltage level Vreg is below a thresholdvalue. For example, the circuit 617 may provide the internal regulatorvoltage to the shunt arm 624 when the voltage Vreg is less than theinternal regulator voltage. Although the circuit 617 includes pFETtransistors, it should be understood that the circuit may include othertypes of transistors in addition, or in alternative, to those shown inFIG. 6.

In certain embodiments, while in an active state, the shunt-arm willhave Vreg (e.g., 2.5 V) or Vcp (e.g., −2.1) as gate voltages. Therefore,according to the configuration of FIG. 6, when the Vreg is powered-up(i.e., the circuit is in an active state), the circuit is effectivelyOFF, wherein a parallel Vreg or Vcp value may be provided to the shuntarm. When Vreg is powered-off, the circuit 617 may effectively be ON,wherein current may flow through the transistors. When the circuit 617is ON, the internal regulator voltage may be provided to the shunt arm624 through the transistors.

FIG. 7 is a graph illustrating potential performance values for stand-bymode isolation for a system incorporating stand-by mode isolation usingan internal voltage regulator, as disclosed herein. As shown, in certainembodiments, more than 6 dB isolation improvement may be achievableusing principles disclosed herein.

FIG. 8 is a graph showing possible improvement in performance for afront-end module implementing stand-by mode isolation, as disclosedherein, compared to a comparable system without such features. The curve801, for example, may represent performance for a system not includingstand-by mode isolation, whereas the curve 802 may represent performancefor a system including stand-by mode isolation, as described herein.

Packaged Module Implementation

In some embodiments, one or more die having one or more featuresdescribed herein can be implemented in a packaged module. An example ofsuch a module is shown in FIGS. 9A (plan view) and 9B (side view). Amodule 810 is shown to include a packaging substrate 812. Such apackaging substrate can be configured to receive a plurality ofcomponents, and can include, for example, a laminate substrate. Thecomponents mounted on the packaging substrate 812 can include one ormore dies. In the example shown, a die 800 having a switching circuit820 and a stand-by mode isolation circuit 817 is shown to be mounted onthe packaging substrate 812. The die 800 can be electrically connectedto other parts of the module (and with each other where more than onedie is utilized) through connections, such as connection-wirebonds 816.Such connection wirebonds can be formed between contact pads 818 formedon the die 800 and contact pads 814 formed on the packaging substrate812. In some embodiments, one or more surface mounted devices (SMDs) 822can be mounted on the packaging substrate 812 to facilitate variousfunctionalities of the module 810.

In some embodiments, the packaging substrate 812 can include electricalconnection paths for interconnecting the various components with eachother and/or with contact pads for external connections. For example, aconnection path 832 is depicted as interconnecting the example SMD 822and the die 800. In another example, a connection path 832 is depictedas interconnecting the SMD 822 with an external-connection contact pad834. In yet another example, a connection path 832 is depicted asinterconnecting the die 800 with ground-connection contact pads 836.

In some embodiments, a space above the packaging substrate 812 and thevarious components mounted thereon can be filled with an overmoldstructure 830. Such an overmold structure can provide a number ofdesirable functionalities, including protection for the components andwirebonds from external elements, and easier handling of the packagedmodule 810.

Wireless Device Implementation

In some implementations, a device and/or a circuit having one or morefeatures described herein can be included in an RF device such as awireless device. Such a device and/or a circuit can be implementeddirectly in the wireless device, in a modular form as described herein,or in some combination thereof. In some embodiments, such a wirelessdevice can include, for example, a cellular phone, a smart-phone, ahand-held wireless device with or without phone functionality, awireless tablet, etc.

FIG. 10 schematically depicts an example wireless communication device900 having one or more advantageous features described herein. Thewireless communication device 900 may include both RF components 995 andbaseband components 990. In certain embodiments, the wirelesscommunication device 900 may include one or more switch devices havingstand-by mode isolation circuitry associated therewith according to oneor more embodiments disclosed herein. In some embodiments, such aswitching device configuration can provide improved stand-by modeisolation.

In the example wireless device 900, a power amplifier (PA) module 901having a plurality of PAs can provide an amplified RF signal to a switch920, and the switch 920 can route the amplified RF signal to an antenna916. In certain embodiments, the switch 920 is connected to stand-byisolation circuitry 917, which may provide an internal regulator voltage919 to the switch 920 during stand-by mode of the switch and/or poweramplifier module 901.

The PA module 901 can receive an unamplified RF signal from atransceiver 906 that can be configured and operated in a known manner.The transceiver 906 can also be configured to process received signals.The transceiver 906 is shown to interact with a baseband sub-system 908that is configured to provide conversion between data and/or voicesignals suitable for a user and RF signals suitable for the transceiver906. The transceiver 906 is also shown to be connected to a powermanagement component 906 that is configured to manage power for theoperation of the wireless device 900. Such a power management componentcan also control operations of various components of the wirelesscommunication device 900.

The switch device 920 may be connected to and/or associated with astand-by isolation circuit 917, as described in detail herein. Thestand-by isolation circuit 917 may be configured to receive a signalfrom an internal regulator, such as a bandgap voltage, and provide theinternal regulator voltage to one or more gates of shunt arm(s) of theswitching device 920.

The baseband sub-system 908 is shown to be connected to a user interface902 to facilitate various input and output of voice and/or data providedto and received from the user. The baseband sub-system 908 can also beconnected to a memory 904 that is configured to store data and/orinstructions to facilitate the operation of the wireless device, and/orto provide storage of information for the user.

In some embodiments, a duplexer 912 a-912 d can allow transmit andreceive operations to be performed simultaneously using a common antenna(e.g., 916). In FIG. 11, received signals are shown to be routed to “Rx”paths (not shown) that can include, for example, one or more low-noiseamplifiers (LNA).

A number of other wireless device configurations can utilize one or morefeatures described herein. For example, a wireless device does not needto be a multi-band device. In another example, a wireless device caninclude additional antennas such as diversity antenna, and additionalconnectivity features such as Wi-Fi, Bluetooth, and GPS.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the above Description using the singularor plural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While some embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

What is claimed is:
 1. A radio-frequency switch comprising: a seriesfield-effect transistor; a shunt field-effect transistor having a gatenode; and shunt arm control circuitry configured to receive an internalregulator voltage and provide the internal regulator voltage to the gatenode of the shunt field-effect transistor when the radio-frequencyswitch is in a stand-by mode of operation.
 2. The radio-frequency switchof claim 1 wherein said providing the internal regulator voltage to thegate node of the shunt field-effect transistor causes the shuntfield-effect transistor to be in an ON state.
 3. The radio-frequencyswitch of claim 1 wherein the internal regulator voltage is between 1.0and 1.5 V.
 4. The radio-frequency switch of claim 1 wherein the shuntarm control circuitry is further configured to receive a voltageregulator voltage and provide the voltage regulator voltage to the gatenode of the shunt field-effect transistor when the radio-frequencyswitch is in an active ON mode of operation.
 5. The radio-frequencyswitch of claim 4 wherein the shunt arm control circuitry is furtherconfigured to provide the voltage regulator voltage to the gate node ofthe shunt field-effect transistor when the voltage regulator voltage isgreater than the internal regulator voltage and to provide the internalregulator voltage to the gate node of the shunt field-effect transistorwhen the voltage regulator voltage is less than the internal regulatorvoltage.
 6. The radio-frequency switch of claim 4 wherein the shunt armcontrol circuitry is further configured to receive a charge pump voltageand provide the charge pump voltage to the gate node of the shuntfield-effect transistor when the radio-frequency switch is in the activeOFF mode of operation.
 7. The radio-frequency switch of claim 4 whereinthe shunt arm control circuitry comprises a control field-effecttransistor, the control field-effect transistor having a gate configuredto receive the voltage regulator voltage and a drain or sourceconfigured to receive the internal regulator voltage.
 8. Theradio-frequency switch of claim 7 wherein the control field-effecttransistor is one transistor of a transistor stack coupled to the gateof the shunt field-effect transistor.
 9. A method of operating aradio-frequency switch comprising: receiving a voltage regulator voltageat a first input node; receiving an internal regulator voltage at asecond input node; receiving a charge pump voltage at a third inputnode; and providing the internal regulator voltage from the second inputnode to a gate of a shunt field-effect transistor of a radio-frequencyswitch when the radio-frequency switch is in a stand-by mode ofoperation.
 10. The method of claim 9 further comprising providing thevoltage regulator voltage from the first input node to the gate of theshunt field-effect transistor when the radio-frequency switch is in anactive ON mode of operation.
 11. The method of claim 10 furthercomprising providing the charge pump voltage from the third input nodeto the gate of the shunt field-effect transistor when theradio-frequency switch is in an active OFF mode.
 12. The method of claim11 wherein, when the radio-frequency switch is in the active ON mode orthe active OFF mode, the voltage regulator voltage is greater than theinternal regulator voltage.
 13. The method of claim 11 wherein, when theradio-frequency switch is in the active ON mode or the active OFF mode,the radio-frequency switch is powered-up.
 14. The method of claim 9wherein, when the radio-frequency switch is in the stand-by mode ofoperation, the radio-frequency switch is not fully powered.
 15. Themethod of claim 9 wherein, when the radio-frequency switch is in thestand-by mode of operation, the internal regulator voltage is greaterthan the voltage regulator voltage.
 16. The method of claim 9 whereinthe internal regulator voltage is generated from a bandgap reference.17. A method of fabricating a semiconductor die comprising: forming aseries field-effect transistor of a radio-frequency switch on asemiconductor substrate; forming a shunt field-effect transistor of theradio-frequency switch on the semiconductor substrate, the shuntfield-effect transistor having a gate node; and coupling the gate nodeof the shunt field-effect transistor to an output node of shunt armcontrol circuitry that is configured to receive an internal regulatorvoltage on an internal regulator voltage input and provide the internalregulator voltage on the output node when the radio-frequency switch isin a stand-by mode of operation.
 18. The method of claim 17 wherein theshunt arm control circuitry is further configured to receive a voltageregulator voltage on a voltage regulator voltage input and to providethe voltage regulator voltage on the output node when theradio-frequency switch is in an ON mode of operation.
 19. The method ofclaim 18 wherein the output node is coupled to a drain or source of afirst transistor of the shunt arm control circuitry, the voltageregulator voltage input being coupled to a gate of a second transistorof the shunt arm control circuitry.
 20. The method of claim 19 whereinthe internal regulator voltage input is coupled to a drain or source ofthe second transistor.